What does it take to make diapers entirely of biobased materials?
The secret is in the use of natural proteins obtained from side streams of current industrial processes, such as starch extraction from potatoes.
5 Oct 2022

According to data from 2019, the disposable diaper market is reaching about USD60 million. 

— The disposable sanitary market, in general, is continuously increasing, says Eva Johansson, scientist and faculty professor at the Swedish University of Agricultural Sciences. More and more people have access to these recourses, and the global population is also growing. Only disposable diapers account for about 50% of the total disposable sanitary market. 

”In the extreme case, we are talking about 1 ton of waste in a year only for one newborn child”

Other data, Johansson explains, shows that at least 2-8 units per day are consumed. 

— In the extreme case, we are talking about 1 ton of waste in a year only for one newborn child. The number of resources used depends on the type of diaper — for newborns, babies, or incontinence for adults — and the manufacturer. To give an assumption, if we take a newborn baby diaper package of 50 units, we are talking about a kilo of materials. Of this kilogram, at least half of it is a superabsorbent polymer and other plastic materials. Such plastic materials are the same type of plastic in traditional plastic bags and are non-biodegradable.

In order to discover alternatives, Sweden’s innovation agency Vinnova joined forces with the Swedish University of Agricultural Sciences, the Royal Institute of Technology, and PhD candidate Antonio Capezza (who’s now graduated) in a project, named ProBlöja.

— We’ve developed protein-based materials with high liquid absorbent capacity. The proteins used were obtained from industrial side streams. The absorbent capacity was within the range of superabsorbents, and the wet properties were relevant for future use in diapers. The properties were reached by functionalizing the proteins to make them more similar to the chemical structure of synthetic superabsorbents used in diapers. The special feature of these materials is that we use a natural polymer (proteins) obtained from side streams of current industrial processes, such as starch extraction from potatoes, which leaves potato protein with no direct food use. In addition, these materials are biodegradable, which allows them to break down in nature in a safe manner. Therefore, there is no plastic accumulation or microplastic formation.

Photography: Antonio Capezza

The current sustainable diaper alternatives on the market are limited. 

— We have, for instance, cloth diapers and diapers where the plastic layers are obtained from renewable resources. However, cloth diapers are only sustainable in countries where water and electricity come from clean sources. In addition, not all customers are willing to use washable diapers or it simply does not adapt to their lifestyles. Other products using plastic from renewable resources only solve the problem of using petroleum-based resources but do not solve the microplastic issue, says Johansson, adding,

— Some companies are trying to replace diaper plastic layers with new solutions. We cooperate with a group at the University of Seville for alternative materials for protein-based superabsorbents. The group is, to our knowledge, the only one in Europe working with these materials. 

What’s the next step?

— We have started by patenting the results obtained. We now have two patents, one of them in cooperation with Essity. Our next step is to continue exploring new materials in our circular bioeconomic concept for this problematic industry and test the current processes on pilot scales. Antonio Capezza, who I mentioned before, is now part of a project which has successfully produced full sanitary pad prototypes that are biodegradable and use proteins and cellulose. The materials developed can be extrapolated to other disposable sanitary products such as diapers. The project has resulted in the creation of a startup, SaniSOLE, aiming to explore how to commercialize these biodegradable and disposable sanitary pads and create the first user platform.